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Biomarkers are Best Indicators of Nutritional Status

By Michael McBurney

Short and sweet. Accurate nutritional assessment requires blood sampling (until other less-invasive measures are developed). Self-reported dietary intake instruments are poorly, in statistical terms the term would be ‘weakly’, correlated with blood biomarkers.

The adjusted correlations between food group reported intake and biomarker status are weak – statisticians define a weak correlation as an r<0.5. With the exception of vitamin C (r=0.58) and DHA (r=0.45) in men, adjusted correlations between reported nutrient intake and biomarker status were r≤0.38. This means that <14% of the total variation in the relationship can be explained. Abysmal.

These men and women living in France have more omega-3 fatty acids and beta-carotene in circulation than Americans. Plasma vitamin C concentrations were similar to those reported in Americans 6y and older, ~ 1mg/dL (56.8 µmol/L). In both France and the U.S., reported intake of fruit and vegetables is far short of recommendations.